I bought a Bambu A1 Mini with the AMS in December 2023. It was supposed to be a present for my son so he could print some things. Well, he never really printed much on it, but I’ve been using it a lot.
After nearly 8 months of printing dozens of projects on it, I finally decided to try printing using the 0.2 mm extruder for a highly detailed print. If you’re not familiar with extruder sizes, here’s a quick breakdown of how I’ve come to understand the extruders:
| Size: | Good for: | Made Out of: |
| 0.8 mm | large projects lacking details; unusual filaments or filaments with additives | hardened steel |
| 0.6 mm | large projects with some big details; unusual filaments or filaments with additives | hardened steel |
| 0.4 mm | smaller projects with details | stainless or hardened steel |
| 0.2 mm | supposedly smaller projects with very fine details | stainless steel |
I’m sure there are some 3D printing pros out there who will disagree with my take on extruder sizes (and, of course, there are a lot of settings that can make extruders more or less useful), but this is how I’ve been thinking about them.
Anyway, I finally had a project that had very fine details and I thought it was time to break out my 0.2 mm extruder. I put it into my A1 Mini with the textured plate, adjusted the settings in the slicer, and started the print.
Royal disaster!
I pretty quickly realized there was a problem. While it was “printing,” it was under-extruding quite a bit. I could also see that the nozzle was scraping up what had previously printed. Basically, the print was a mess and looked terrible. I thought the 0.2 mm extruder was going to deliver something beautiful, but what I got instead was a disaster of a print that I ended up stopping after just a few minutes because it looked terrible.
I spent about 8 hours troubleshooting this and learned the following:
First, given the layer heights for my print, the textured plate was part of the problem. If the textured plate has bumps on it that are, say, 0.1 mm in size and the layers are smaller than that, the extruder will, in fact, hit the plate, which is what was happening. So, a smooth plate was necessary. I was able to solve that problem.
Second, the extruder gear in the A1 Mini does not appear to be strong enough to actually push the filament through the 0.2 mm extruder. With the larger extrusion tips, there are no issues pushing the filament through, even when printing at slower speeds. I’ve learned that finer quality typically requires slower speeds. But, if you do that with the 0.2 mm extruder, the gear slips on the filament as it is extruding so slowly that it can’t actually push the filament through the tip. As a result, the pressure on the filament to extrude is reduced and you get under-extrusion. I tried solving this by: (a) increasing the temperature of the extruder, and (b) speeding up the print speed so more filament would be pushed out. Neither approach solved the under-extrusion problem.
FYI, all of my experimentation was done with Bambu Labs PLA (basic). So, this wasn’t a filament issue. This is a design issue.
At this point, I’m open to suggestions, but I’m fairly convinced that the A1 Mini is just not capable of printing with a 0.2 mm extruder, which is a damn shame since this machine is great in so many other ways and would be ideal for printing mini-figures and other items like that. I’m guessing the other Bambu Labs machines have stronger gears that don’t slip, which would solve the under-extrusion issue.
